Coordinates: 51°42′54″N 3°50′46″W / 51.715°N 3.846°W
Alltwen (or Allt-wen) – meaning "white wooded slope" – is a village in the county borough of Neath Port Talbot, Wales, near Pontardawe in the Swansea Valley. Alltwen is served by Alltwen Primary School and is home to rugby union club Alltwen RFC.
Alltwen was the home village of Ronnie James, British Lightweight Boxing Champion in the 1940s and World Title challenger in 1946. The Welsh character actress Rachel Thomas was born in the village and the film, television, and stage actress Siân Phillips also spent much of her childhood there.
Local pubs include:
Allt-wen is an electoral ward of Neath Port Talbot county borough and is a part of the community of Cilybebyll. The ward is bounded by Trebanos and Pontardawe to the northwest; Rhos to the northeast; Bryn-côch North to the southeast; Dyffryn to the south; and Clydach (in Swansea) to the southwest.